The present invention relates to a system and a method for providing information on the time taken to read a file, as well as a program for executing the method.
Examples of a storage device for storing data include a solid state drive (SSD), a hard disk drive (HDD), and a magnetic tape medium (hereinafter simply referred to as tape). The storage device stores data as a file. The file is managed with a file system using information (metadata) on the file as an index.
If a tape is used as a storage device, for example, a linear tape file system (LTFS) is used as the file system. When a file is recorded on a tape in the LTFS format, it takes several minutes to scan the tape from one end to the other end because tape is a long recording medium extending in one direction, and thus read time varies significantly depending on the recording position of the file on the tape.
Internet Explorer® provided by Microsoft® obtains the time taken to transfer a file by measuring a file transfer rate after starting the transfer and dividing the size of the file by the transfer rate and provides information on the time by means of display or the like.
In the case of tape, the time for a reading head to move to a file recording position on the tape (seek time) is needed before file transfer is started, during which the time taken for the transfer cannot be updated. Furthermore, with the LTFS, if data is added to the tape, fragments of the data are separately recorded on a plurality of positions of the tape. Thus, the LTFS reads the data while seeking all the fragments. This makes it difficult to predict the time from the start of reading the file to the end thus making it impossible to provide correct read time.
To predict the time taken to read a file on a tape, a method for calculating the time taken to read data recorded on a tape in a tape library has been proposed (for example, see PCT International Publication No. WO2010/035617).